Abstract:Effects of roasting process conditions on extraction of molybdenum with ammonia were investigated. Molybdenum calcine and leaching residues were characterized by means of XRD and SEM. The results show that under low roasting temperature, both leaching rate and recovery of molybdenum are low due to incomplete oxidation of molybdenum concentrates. Leaching rate remains high but molybdenum recovery is low when roasting temperature is too high. Leaching rate and recovery rise firstly with increase of roasting time and then remain nearly stable. Leaching rate of molybdenum calcine is 93.54% under the conditions including roasting temperature of 600 ℃, roasting time of 2 h, and appropriate leaching condition. Leaching rate can be improved to 97.5% by addition of some sodium carbonate in leaching solution. Leaching residues mainly contain CaMoO4 and SiO2.